1. Field of the Invention
The present invention relates generally to pipe lining techniques, and more particularly, to a pipe lining method for lining a defective or old pipeline with a pipe liner bag for repairing same.
2. Description of the Related Art
When an underground pipe, such as pipelines and passageways, becomes defective or too old to perform properly, the pipe is repaired and rehabilitated without digging the earth to expose the pipe and disassembling the sections of the pipe. This non-digging method of repairing an underground pipe has been known and practiced commonly in the field of civil engineering. The pipe lining method utilizes a tubular pipe liner bag made of a resin absorbent material impregnated with a hardenable resin, and having the outer surface covered with a highly air-tight plastic film. The tubular pipe liner bag is inserted into a pipe to be repaired by means of a pressurized fluid such that the pipe liner bag is turned inside out as it proceeds deeper in the pipe. Hereinafter, this manner of insertion shall be called "everting". When the entire length of the tubular liner bag is everted (i.e., turned inside out) into the pipe, the everted tubular liner is pressed against the inner wall of the pipe by a pressurized fluid, and the tubular flexible liner is hardened as the hardenable resin impregnated in the liner is heated, which is effected by heating the fluid filling the tubular liner bag. It is thus possible to line the inner wall of the defective or old pipe with a rigid liner without digging the ground and disassembling the pipe sections.
In the conventional pipe lining method as mentioned above, cutting tools such as sander, a saw, and so on are utilized to manually cut portions of a hardened pipe liner bag which block an inlet and an outlet of a repaired pipe or an opening to a branch pipe.
In particular, since a man cannot enter into pipelines having an inner diameter equal to or smaller than 800 m/m, a remotely operable robot is utilized for cutting a portion of a pipe liner bag, applied to line such a relatively small pipeline, which blocks an opening to a branch pipe. The robot may be controlled on the ground.
However, manual cutting operations of line liner bags utilizing cutting tools cause chips to disperse around the operation site, thus introducing deteriorated operation environment. Particularly, such operations for a sewage line must be performed within a narrow man hole of 900 m/m in diameter, so that the operability is quite low.
In the cutting operation utilizing the robot for piercing a pipe liner bag, in turn, the robot must be remotely operated, so that the robot might damage a branch pipe or a branch pipe liner bag depending on a mounting situation of the branch pipe and a process of operating the robot.